Brave won't share your data, we use a ZKP protocol, ANONIZE2 (2nd generation https://anonize.org/) and we're aiming to decentralize via ZK-STArKs in state channels, or better, on future Ethereum. Sharing data even with consent leaks too much, and scale players can arbitrage and abuse users across media and devices, even with Brave protecting by default. So we won't share data even optionally. Users may share by forming first-party relationships with brands, but only if they choose to do so.

We've tied the knot between user agent and user interests by (a) blocking by default, any private ads are opt-in per user; (b) all user identifying data stays on device and never goes to our servers in linkable form; (c) user gets at least as much revenue share as we get: 70% to our 30% for private tab ads; 15/15 split between us and user with 70% to the publisher if we get to filling publisher ad slots (note we use transparent, macro-auditable-on-blockchain fees, unlike most of the ad-tech parasites).